The invention relates to turbine engine blades or vanes made of composite material comprising fiber reinforcement densified by a matrix. The invention relates also to compressor stator segments and turbine nozzle segments incorporating such composite material vanes.
The intended field is that of gas turbine blades or vanes for aeroengines or industrial turbines.
Proposals have already been made to fabricate composite material blades for turbine engines. Reference may be made in particular to patent applications FR 2 939 129 and FR 2 939 130 filed jointly by Snecma and Snecma Propulsion Solide. Those applications describe in particular fabricating a turbine engine blade out of composite material comprising fiber reinforcement densified by a matrix. More precisely, the method described in those two documents and applied to fabricating a blade presents the special feature of a fiber blank that is made by three-dimensional weaving and that is shaped in order to obtain a single-piece fiber preform with a first portion forming a preform for a blade root and an airfoil, and at least one second portion forming a preform for an inner or an outer platform of the blade. Thus, once the preform has been densified, it is possible to obtain a composite material blade having fiber reinforcement constituted by the preform and densified by the matrix, and forming a single piece that has an inner or an outer platform incorporated therein.
The blade obtained by such a method presents the drawback that its outer platform cannot incorporate both a function of providing sealing with the casing that surrounds the blades (by having wipers present) and an aerodynamic function (by having overhangs present that define the outside of gas flowpath through the turbine). Furthermore, at its root, the overhangs of the inner blade platform that is obtained by that method can break under the effect of the high levels of force to which they are subjected in operation (this force being due to the centrifugal force of rotation).
Use of CMC materials has also been proposed for turbine nozzles, in particular in application WO 2010/146288.
A conventional metallic turbine nozzle or compressor stator is formed of several assembled sectors, each sector comprising an inner platform, an outer platform and a plurality of airfoils extending between the inner and outer platforms and integral therewith. The inner and outer platforms delimit the gas or air flow passage in the turbine nozzle or compressor stator. On the outside, the outer platforms of the segments are formed integrally with legs allowing the mounting of the turbine nozzle or compressor stator in a casing.